<reasoning_content>
The user wants a basic job queue implementation in Python.
Requirements:
- `JobQueue` class
- `add_job(job_id: str, data: dict) -> str`: adds a job, returns job_id
- `get_result(job_id: str) -> dict | None`: gets result of a completed job
- FIFO order processing
- Stores jobs internally until processed
- Each job has a unique job_id (though the example shows passing one in, the requirement says "unique job_id that is returned when added", but the signature takes `job_id` as argument. I'll stick to the signature provided but ensure it handles the ID properly. Actually, the example shows `queue.add_job("job1", {"task": "process_data"})`, so the job_id is provided by the caller. I'll just use the provided ID.)

I need to simulate processing. Since it's a "basic" queue, I'll add a `process()` or similar method to actually process jobs, or maybe the user expects the processing to be handled externally or via a method. The prompt says "Jobs should be processed in FIFO order", but doesn't specify how processing happens. I'll add a `process()` method that processes the next job and stores the result. Or maybe `process_all()`. Let's add a `process()` method that takes a function or just simulates processing by storing a result. Actually, for a basic queue, I can just store the job and have a method to simulate processing, or assume the user will call a process method. I'll add a `process()` method that processes the first job and stores a dummy result, or better, allows a processing function. But the requirement says "basic job queue", so I'll just implement the queue storage and a simple process method that stores a result like `{"status": "completed", "data": job_data}`.

Wait, the example shows:
```python
queue = JobQueue()
job_id = queue.add_job("job1", {"task": "process_data"})
# After processing...
result = queue.get_result("job1")
```
This implies there should be a way to process jobs. I'll add a `process()` method that processes the next job in the queue and stores its result. To keep it simple, I'll just mark it as completed and store a result dict.

Let's design the class:
```python
from collections import deque

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results = {}

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append((job_id, data))
        return job_id

    def process(self):
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> dict | None:
        return self._results.get(job_id, None)
```

Wait, the requirement says "Each job has a unique job_id that is returned when added". The example passes `"job1"` as the first argument. That's fine.
I should make sure type hints match the prompt: `job_id: str, data: dict) -> str` and `get_result(job_id: str) -> dict | None`.
In Python 3.9+, `dict | None` is valid. I'll use `Optional[Dict]` or `dict | None` as requested. I'll stick to `dict | None` as it's in the prompt.

Is there any need for thread safety? The prompt doesn't specify, so I'll keep it simple.
Should I include `from typing import Optional, Dict`? The prompt uses `dict | None`, which is Python 3.10+ syntax. I'll just use it as is, or use `Optional` to be safe, but I'll follow the prompt's type hint style.

Let's refine:
```python
from collections import deque
from typing import Optional, Dict

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results: Dict[str, dict] = {}

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append((job_id, data))
        return job_id

    def process(self) -> None:
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id, None)
```

Wait, the prompt says `get_result(job_id: str) -> dict | None`. I'll use exactly that in the signature if possible, or `Optional[dict]`. I'll stick to `dict | None` for modern Python, but `Optional[dict]` is safer for compatibility. I'll just use `dict | None` as requested.

Actually, the prompt might just want the queue implementation without a process method, but it says "Jobs should be processed in FIFO order". I'll add a `process()` method. Or maybe the processing is implicit? No, queues need a way to process. I'll add `process()` and maybe `process_all()`.

Let's check the example again:
```python
queue = JobQueue()
job_id = queue.add_job("job1", {"task": "process_data"})
# After processing...
result = queue.get_result("job1")
```
The comment "# After processing..." implies the user will call a process method. I'll add `process()` and `process_all()`.

To be strictly compliant with "Write only the Python code, no explanations.", I'll just output the class.

One thing: `dict | None` is valid in Python 3.10+. I'll use it.
I'll also make sure the result returned by `get_result` matches what's expected. The prompt says `-> dict | None`.

Let's write it out carefully.

```python
from collections import deque
from typing import Optional

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results = {}

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append((job_id, data))
        return job_id

    def process(self) -> None:
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id, None)
```

Wait, should `get_result` return exactly `dict | None`? I'll use `dict | None` in the type hint to match the prompt.
Also, I'll add `process_all` just in case, but `process` is enough.
The prompt says "Jobs should be processed in FIFO order". The `popleft()` handles that.
I think this is sufficient.

Let's double check the exact prompt: "Write only the Python code, no explanations."
I will output just the code.

One minor point: `dict | None` might cause a syntax error in Python < 3.10 if not using `from __future__ import annotations`. I'll just use `Optional[dict]` or `dict | None` with `from __future__ import annotations` to be safe, or just stick to `dict | None` as modern Python supports it. I'll use `dict | None` directly.

Actually, I'll just write:
```python
from collections import deque
from typing import Optional

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results = {}

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append((job_id, data))
        return job_id

    def process(self) -> None:
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id, None)
```

Wait, the prompt says `get_result(job_id: str) -> dict | None`. I'll change the return type to `dict | None` to match exactly. Python 3.10+ handles it. I'll assume modern Python.

I'll also add a `process_all` method for convenience, but it's not strictly required. I'll stick to `process()`.

Is there any ambiguity about "processed"? Usually, a job queue needs a worker or a process method. I'll keep `process()`.

One thing: the example shows `queue.add_job("job1", {"task": "process_data"})`. The first argument is named `job_id` in the signature, but in the example it's passed positionally as `"job1"`. That's fine.

I think this is good. I'll output just the code.
I'll make sure imports are included.
Final code:
```python
from collections import deque
from typing import Optional

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results = {}

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append((job_id, data))
        return job_id

    def process(self) -> None:
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id, None)
```
Wait, `Optional[dict]` vs `dict | None`. I'll use `dict | None` to match the prompt exactly.
Also, I'll add `from __future__ import annotations` to ensure compatibility if needed, but it's optional. I'll skip it for brevity unless necessary. Python 3.10+ is standard now.

Let's stick to the prompt's type hints.
I'll output exactly the code.
One detail: `get_result` returns `dict | None`. I'll use that.
Done. 
I will generate the response now. 
Self-Correction/Refinement during thought:
The prompt says `get_result(job_id: str) -> dict | None`. I'll use exactly that.
I'll also make sure the code is clean.
Should I include a way to simulate processing without a `process()` method? The prompt says "Jobs should be processed in FIFO order", which implies an internal mechanism or a method. `process()` is standard.
I'll provide the class as requested.
All good. 
Output matches the refined code. 
Proceeds. 
```python
from collections import deque
from typing import Optional

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results = {}

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append((job_id, data))
        return job_id

    def process(self) -> None:
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id, None)
```
Actually, I'll change `Optional[dict]` to `dict | None` to strictly match the prompt, and add `from __future__ import annotations` if I want to be safe, but it's fine either way. I'll just use `dict | None`.
Wait, `typing.Optional` is more compatible. I'll stick with `Optional[dict]` or just `dict | None`. The prompt uses `dict | None`, so I'll use that.
I'll output exactly what's needed.
Done. 
Proceeds. 
[Output Generation] -> *Self-Correction/Verification during generation prep*:
The prompt says `get_result(job_id: str) -> dict | None`. I will use that.
I'll also add `process_all()` just in case, but it's not required. I'll keep it simple.
The code is ready.
Output matches. 
Proceeds. 
[Final Check]
- Class `JobQueue`? Yes.
- `add_job` signature matches? Yes.
- `get_result` signature matches? Yes.
- FIFO order? Yes, `deque.popleft()`.
- Stores internally? Yes.
- Unique job_id returned? Yes.
- Only Python code, no explanations? Yes.
All constraints met.
Output matches response. 
Proceeds. 
```python
from collections import deque
from typing import Optional

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results = {}

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append((job_id, data))
        return job_id

    def process(self) -> None:
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> Optional[dict]:
        return self._results.get(job_id, None)
```
I'll change `Optional[dict]` to `dict | None` to exactly match the prompt, and assume Python 3.10+. It's fine.
Final code:
```python
from collections import deque

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results = {}

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append((job_id, data))
        return job_id

    def process(self) -> None:
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> dict | None:
        return self._results.get(job_id, None)
```
This is clean and matches requirements. Output matches.✅
Proceeds. 
[Output Generation] (matches the final code block)
Note: I'll keep `from typing import Optional` out since I'm using `dict | None`. It's standard in 3.10+. If compatibility is a concern, `Optional` is safer, but the prompt explicitly uses `dict | None`. I'll stick to `dict | None`.
Done. 
Output matches response. 
[Final Output Generation] -> *Proceeds*

</reasoning_content>

<content>
```python
from collections import deque

class JobQueue:
    def __init__(self):
        self._queue = deque()
        self._results = {}

    def add_job(self, job_id: str, data: dict) -> str:
        self._queue.append((job_id, data))
        return job_id

    def process(self) -> None:
        if self._queue:
            job_id, data = self._queue.popleft()
            self._results[job_id] = {"status": "completed", "data": data}

    def get_result(self, job_id: str) -> dict | None:
        return self._results.get(job_id, None)
```
</content>